Semiconductor device having a temperature sensor

Abstract

A semiconductor device is provided that includes a temperature sensing function that accurately senses a temperature. The semiconductor device includes a first semiconductor layer on a semiconductor substrate, and a temperature sensor. The temperature sensor includes: a sensing-body region of a second conductivity type that is disposed in the first semiconductor layer; a first region of a first conductivity type, and a second region of the first conductivity type that are arranged in the sensing-body region and are apart from each other; and a third region of the second conductivity type that is in the sensing-body region and is between the first region and the second region. A concentration of a first conductivity type impurity in the temperature-sensing conductive layer is higher than a concentration of a first conductivity type impurity in the drift region.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a semiconductor substrate of a first conductivity type; 
 a first semiconductor layer that is on a main side of the semiconductor substrate, and includes a main area and a temperature sensing area on the main side; 
 a plurality of unit cells arranged in the main area and connected with each other in parallel; and 
 a temperature sensor disposed in the temperature sensing area, wherein 
 each of the plurality of unit cells includes: 
 a main-body region of a second conductivity type that is disposed in the first semiconductor layer, and is in contact with a surface of the first semiconductor layer; 
 a source region of the first conductivity type that is in the main-body region; 
 a drift region of the first conductivity type disposed in a region of the first semiconductor layer except the main-body region and the source region; 
 a gate insulating film disposed on the first semiconductor layer; 
 a gate electrode disposed on the gate insulating film; 
 a source electrode disposed on the first semiconductor layer, and electrically connected with the source region; and 
 a drain electrode disposed on a back side of the semiconductor substrate, 
 the temperature sensor includes: 
 a sensing-body region of the second conductivity type that is disposed in the first semiconductor layer, and is in contact with the surface of the first semiconductor layer; 
 a first region of the first conductivity type, and a second region of the first conductivity type that are arranged in the sensing-body region and are apart from each other; 
 a third region of the second conductivity type that is in the sensing-body region and is between the first region and the second region; 
 a temperature-sensing conductive layer of the first conductivity type that is disposed on the first semiconductor layer, and is in contact with part of the first region, the third region, and part of the second region; 
 a first electrode electrically connected with the first region and the sensing-body region; and 
 a second electrode electrically connected with the second region, and 
 a concentration of an impurity of the first conductivity type in the temperature-sensing conductive layer is higher than a concentration of an impurity of the first conductivity type in the drift region. 
 
     
     
       2. The semiconductor device according to  claim 1 , wherein
 the temperature sensing area further includes a separating portion that electrically separates the temperature sensor from the plurality of unit cells in the main area, and 
 the separating portion includes: 
 a separating-body region of the second conductivity type that is disposed in the first semiconductor layer, is apart from the sensing-body region, is in contact with a surface of the first semiconductor layer, and is electrically connected with the source electrode; and 
 a fourth region of the first conductivity type that is part of the first semiconductor layer and is between the separating-body region and the sensing-body region. 
 
     
     
       3. The semiconductor device according to  claim 2 , wherein
 the separating portion further includes a separation assisting layer of the first conductivity type that is disposed on the first semiconductor layer, and is in contact with the fourth region, 
 a concentration of an impurity of the first conductivity type in the separation assisting layer is higher than a concentration of an impurity of the first conductivity type in the drift region, and 
 the separation assisting layer is electrically separated from the temperature-sensing conductive layer. 
 
     
     
       4. The semiconductor device according to  claim 2 , wherein a concentration of an impurity of the first conductivity type in the fourth region is higher than a concentration of an impurity of the first conductivity type in the drift region. 
     
     
       5. The semiconductor device according to  claim 1 , wherein a concentration of an impurity of the first conductivity type in the temperature-sensing conductive layer ranges from 1×10 17  cm −3  to 1×10 19  cm −3  inclusive. 
     
     
       6. The semiconductor device according to  claim 1 , wherein the temperature-sensing conductive layer has a shape like an island. 
     
     
       7. The semiconductor device according to  claim 1 , wherein when the first region is seen in a direction perpendicular to the main side of the semiconductor substrate, the first region is disposed in such a manner that the first region surrounds the second region, and the third region is disposed between the first region and the second region. 
     
     
       8. The semiconductor device according to  claim 1 , wherein
 each of the plurality of unit cells further includes a channel layer of the first conductivity type, and the channel layer is disposed between the first semiconductor layer and the gate insulating film in such a manner that the channel layer is in contact with at least the main-body region, and 
 a concentration of an impurity of the first conductivity type in the channel layer is higher than a concentration of an impurity of the first conductivity type in the drift region. 
 
     
     
       9. The semiconductor device according to  claim 1 , wherein
 the temperature sensor further includes a sensing-body contact region of the second conductivity type that is in the sensing-body region, and a concentration of an impurity of the second conductivity type in the sensing-body contact region is higher than a concentration of an impurity of the second conductivity type in the sensing-body region, and 
 the sensing-body contact region is in contact with the first electrode. 
 
     
     
       10. The semiconductor device according to  claim 1 , wherein the main-body region and the sensing-body region have an equal concentration profile of an impurity of the second conductivity type in depth directions of the main-body region and the sensing-body region. 
     
     
       11. The semiconductor device according to  claim 1 , wherein the first semiconductor layer is a silicon carbide semiconductor layer.